FIG. 1 schematically shows a structure of a backlight module in the prior art, wherein a path of a light transmitting in a light guide plate 1 is shown. As shown in FIG. 1, in the prior art, the backlight module consists of a Light-Emitting Diode (LED) light source 2 and a Light Guide Plate (LGP) 1. A main body of said light guide plate 1 comprises a light-exiting surface 12 (which can be seen as a top surface), a light-reflecting surface 11 (which can be seen as a bottom surface) that is opposite to said light-exiting surface 12, and four lateral surfaces (which are a first lateral surface 13, a second lateral surface 14, a third lateral surface, and a fourth lateral surface respectively) that are arranged between said light-exiting surface 12 and said light-reflecting surface 11. The whole region of the light-reflecting surface 11 is provided with lattice-points 111′, while the light-exiting surface 12 is not provided with any lattice-point. In practical applications, such as a screen of a mobile phone comprising said backlight module, due to the coverage of a frame or other parts of the mobile phone, only part of the area in the light-exiting surface 12 of the light guide plate main body is a visible area. That is, the area of the light-exiting surface 12 that is not covered by the frame is the visible area.
With the development of consumer electronic products, the frames of these products, such as mobile communication products and tablet personal computers, are becoming increasingly narrow. In the designing of electronic products with a narrow frame, since the distance between the edge of the light guide plate 1 and the edge of the visible area is rather small, an edge reflective effect would be generated. As shown by the light transmitting path in FIG. 1, specifically, an arrow P1 in FIG. 1, the light, which is emitted by the LED light source 2, enters into the light guide plate main body through the first lateral surface 13 thereof, and refracts out through an edge of the light-exiting surface 12 of the light guide plate main body after the reflection of the second lateral surface 14 of the light guide plate main body, so that the edge reflective effect would be generated. The edge reflective effect would result in that the peripheral portion of the visible area looks brighter, and thus a striking bright belt surrounding the edge of the visible area would be resulted. Consequently, the display effect of the electronic products would be seriously affected.
A technical solution for eliminating the bright belt is proposed in the prior art, that is, a light-absorbing processing can be performed in the region of the light-exiting surface 12 where the bright belt could be generated. Specifically, in the above technical solution, black double-sided adhesive is applied on said region, or ink is sprayed thereon. By virtue of the light absorption effect of these black materials, the bright belt can be totally absorbed. However, the defect of this method lies in that the light-absorbing processing would inevitably result in light losses thereof.